Photolithography-Enabled Au/Si Columnar Array Photoelectrochemical Sensor for High-Performance Nitrite Detection

In this work, we demonstrate the fabrication of gold-decorated silicon column array (Au/SiCAs) photoanodes for photoelectrochemical (PEC) nitrite detection. The SiCAs were synthesized on n-type silicon substrates via photolithography and anisotropic etching, after which Au nanoparticles were deposited by magnetron sputtering. The Au/SiCAs photoanodes exhibited a pronounced PEC photocurrent response under the simulated solar irradiation. For nitrite determination, the sensor achieved two broad linear ranges (10-500 μM and 2000-10,000 μM) with corresponding sensitivities of 0.25 and 0.33 μA·μM^-1·cm^-2, along with a detection limit of 0.25 μM (S/N = 3). Moreover, the sensor exhibited excellent selectivity, remarkable stability, and facile fabrication. Successful detection in real sample confirms its potential for practical applications. This study proposes a novel approach for precise and reliable PEC-based nitrite analysis.